I am working on studies to identify the molecular mechanisms of important biological phenomena and diseases and to provide a logical basis for the treatment of the diseases. I found that mutations on the pink-eyed dilution gene are responsible for oculocutaneous albinism II. I have studied protein tyrosine kinases (PTKs) for the regulation of catalytic activities and signaling pathways for tumorigenesis and developed small molecule inhibitors for the PTKs. I recently developed neutralizing antibodies against PTK7, a catalytically defective receptor-type PTK, and am analyzing its potential as a new drug for targeted cancer therapy. To understand the function of extracellular proteolytic enzymes, such as matrix metalloproteinases, their substrates have been identified by proteome analysis of extracellular proteins, and the relationships between substrate degradation and disease are investigated. In addition, genes involved in skin aging have been screened by transcriptome analysis of young and old dermal tissues and molecular mechanisms of skin aging have been investigated. As a result, more than 100 articles have been published in prestigious international journals.